The access of the end users to information technologies and to the digital services that these provide is conditioned by various factors and problems.
One of the problems is the geographical location of the users, as it can condition the availability of said digital services, depending on the telecommunications deployment in each area. For example, not all inhabited areas have a communication network deployment such as XDSL, FTTH, ISDN, GSM, GPRS, 3G, 4G, etc.
Another problem is the socio-economic situation of the users, as access to said aforementioned communication networks depends, in most cases, on subscription charges with different business models (fixed payment, pay-per-use, prepayment, etc.) which not all digital service users can assume. Among the socio-economic factors, users' age and education are conditioning factors since, due to lack of knowledge and feeling of difficulty in the use of new technologies, there are certain social groups that may be excluded from accessing these advanced digital services.
An additional problem is the complexity of accessing the enormous amount of information currently available and which makes it difficult to find the information that is really important or useful.
Furthermore, in recent years, the improvement in telecommunications services and the evident associated economic savings and resources, has given rise to many initiatives to achieve the development of so-called Smart Cities, understood as cities that propose investing in aspects such as energy infrastructures (electricity, gas, etc.), transport or communication technologies (electronics, Internet, Internet of Things, etc.) to promote better quality of life and a lasting and sustainable economic-environmental development. But most of these initiatives are encountering some or all of the aforementioned barriers. These initiatives, promoted mainly by public administrations, are sparking commercial interest in reaching end users. This access always depends on the end user and his or her willingness to or possibility of subscribing to the services offered.
Current conventional video intercom systems, generally composed of an installation of two-wire buses and distinguishing them from those incorporating IP technology, do not have an infrastructure which allows them to provide advanced digital services, as the installation bus, when it exists, allows a very limited flow of information and is restricted to the transmission of a number of basic commands or messages, since they are systems which, generally, by means of a non-polarised two-wire communications line, communicates with a plurality of home terminals having an intercom and/or image display monitor, to transmit audio, video and data over the communication line, such that they are capable of holding a conversation between two elements of the installation, transmitting two audio channels via said two wires (upstream audio and downstream audio), one video channel (normally upstream) and one data channel for system management. In this type of system, low-performance and low-cost elements can coexist (only audio communication) with other high-performance elements (audio and video communication) wherein the cost is not so limiting.
A separate case is that of video intercom systems having IP technology, which do allow this flow of high-performance information, including bandwidth, but its implementation is very limited due to the high deployment costs, as they do not work with the usually available cabling. For example, solutions with IP technology are usually implemented over more complex and expensive infrastructures such as:                Structured cabling (CAT-5), which requires specific cabling and distribution or switching elements (switches), entailing high costs, which do not allow the reuse of existing cabling based on simplified installation two-wire buses.        The use of PLC (Power Line Communications) modems is also known in IP-based video intercom systems. These modems use the power supply to convert it into a high-speed digital data transmission line and leverage the existing cabling but require the use of an expensive modem in each device; in addition, the number of nodes is very limited.        Lastly, another alternative for implementing these IP-based video intercom systems would be through Wi-Fi networks, which requires a Wi-Fi module per device, with the ensuing cost and added problem that the distances at which they can be accessed are limited.        
Therefore, these types of solutions are mainly focused on single-user video intercom systems (home, office, etc.), where this system is combined with the existing IP network in the household and which is accessed over XDSL, optical fibre, coaxial cable, etc., and therefore cannot be extrapolated to multi-user or multi-dwelling solutions.
One of the main problems of conventional video intercom systems based on two-wire buses is the use of the communication channel.
There are alternatives which allow the use of the video intercom infrastructure or system to access multimedia services on video intercom monitors through the display of on-screen menus generated by means of images in an external device, but at the cost of occupying the communication channel, whereupon the video intercom and information service cannot be used simultaneously.
Patent ES-2170682-B1 relates to an installation of an audio door entry system and, additionally, video intercom, with bi-directional access to the telephone line, through any dual-tone multi-frequency telephone (DTMF), making it possible to communicate and/or open the door from any of them using the corresponding outdoor entry panel bi-directionally and enabling switching between different communications established, but that requires incorporating two additional wires to provide a video signal.
Patent application EP-1955486-A1 shows a video intercom system having multimedia functions with external information sources that reach the user via the two-wire bus infrastructures, but where it is limited to a single user who can access the service each time, or is limited to a local connection within the dwelling to a multimedia player, and also without using the infrastructure of the building of the video intercom system.
Document US-20120028589-A1 shows an interactive method and system for monitoring dwellings through facial recognition which includes communication with a multimedia content distribution network by means of a video intercom. Although the system of this document seems to show simultaneous access to advanced multimedia services to a plurality of users, the system disclosed does not allow its implementation through a two-wire bus infrastructure and, on the contrary, is supported by a specific element for managing multimedia content.
Furthermore, the most extended use in the connectivity of building installations is that of remote management of domotic systems and alarms, such as those shown in patent applications US-2013297259-A1 or US-2008279202-A1. In these applications, individual connectivity systems in each dwelling are used for remote management and do not actually use the video intercom installation infrastructure to perform said management and which, therefore, does not allow the simultaneous management of the audio and video intercoms of various dwellings, as in the case of an office or residential building.
There are devices that can be assimilated to the communications gateway concept presented in this invention to the extent that some of the components or modules are typical in these types of systems (such as for example a processor, a signal conversion or input and/output ports), but clearly have different functionalities or applications. For example, utility model CN-201215979-Y is directly aimed at a gateway in the form of a set-top-box or IPTV signal decoder having a wireless interface; or document CN-101977192, which discloses a gateway for medical applications and which enables the connection, on the one hand, of the devices or sensors of a user, mainly over Zigbee protocol and, on the other, provides IP connectivity.
There are other types of gateways more proximate to video intercom systems, such as that disclosed in document EP-2556629-A1, where the gateway enables, as opposed to the solution proposed in the present invention, the connection of end user devices such as PCs, tablets, mobile phones, etc. to the video intercom system to receive/send the audio and/or video signal of the video intercom system; therefore, they are not aimed at offering advanced digital services by accessing them through an Internet connection to a specific system that offers and manages said services.
Another significant example is patent application WO-2012066397-A1, which discloses a system that offers a video intercom service and additionally provides services accessible via the Internet, essentially for managing domestic sensors and where there is a gateway for said access. Said gateway is connected to the outdoor panel of the video intercom system and is in charge of routing the call towards the terminals of each dwelling, using for such purpose TCP/IP routing; therefore, all communication is over TCP/IP, both internal system communication and outgoing communication, towards the Internet. Therefore, said gateway is essential both for providing the video intercom service and for external access and implies a critical point for the entire system in the event of failure. This document shows the use of twisted pair as cabling, i.e. it is assimilated to a CAT-5 cable, and therefore the system is not adapted for operating with the wires of a traditional video intercom installation. The information shown by the terminals of the dwellings and accessibility to the external services is carried out through web pages managed by a web client in the terminal itself.